In my teens (90s) I knew an overweight girl who would eat hersheys chocolate syrup straight from the bottle as a "dieting" snack. Her understanding was that it was fat-free, hence non-fattening.

It's sad how much this misunderstanding of fat being fattening has permeated the US population to this day. All the false/misleading information in product advertising has definitely played a significant role, it should be made illegal and enforced with stiff fines.